This topaz crystal is from Minas Gerais, Brazil. Minas Gerais has many areas that contain pegmatite deposits which are mined for various gemstones including topaz. It s a silicate that contains the elements Al, Si, F, O and H. Pure crystals are colorless but it can be found in a variety of colors depending on the trace elements incorporated in the crystal lattice. This is colorless crystal with a glass luster and lightly etched prism surfaces. The termination is pinacoid. The exterior contains minor clay and oxide deposits. The interior is transparent with areas of veiling and flaws. This crystal measures 3 5/16 x 2 x 1 1/8 inches or 85 x 50 x 28 mm.